Dental prosthetic procedures for replacing one or more teeth with dental restorations, such as crowns and bridges, are performed on a daily basis by dentists worldwide. In cases where a patient's original tooth is either missing or is ill or damaged to an extent where it no longer can serve as the support for a dental restoration, the dentist may decide to place an implant in the patient's jaw bone, such that the dental restoration can be supported by this implant e.g. via an implant abutment. When arranged in the patient's mouth implants can replace the parts of the teeth which are not visible in a 3D surface scan, such as the roots of the tooth. If the original tooth or any remains of it still are present in the patient's mouth these are extracted and a bore for the implant is surgically drilled into the jaw bone. The implant is placed in this bore and the surrounding bone grows into very close apposition to the implant such that the implant is secured to the bone. This process is also known as osseointegration. In particular titanium has shown to have very good osseointegration properties and is currently the most preferred material to use for implants.
Osseointegration usually takes several months to complete and during that period of time a healing abutment can be placed at the implant in order to e.g. ensure that the implant is kept free of dirt and food. The healing abutment can further be used for shaping the soft tissue in the region where the original tooth was extracted from such that the soft tissue maintains an anatomically correct shape instead of collapsing into the space which previously was occupied by the extracted tooth.
Once the osseointegration is completed and the implant is secured in the bone such that it can be used as support for dental restorations, the healing abutment is removed and the final dental restoration is arranged in the implant. This is often an implant abutment placed in the implant to serve as an interface between the implant and an anatomical layer, such as a crown or a bridge, and coping layers. The implant abutment can be secured in the implant using a retention screw and the anatomical layer can be cemented to the implant abutment.
Several implants are provided with an internal anti-rotational feature which can be engaged by a corresponding feature of a so-called engaging abutment such that rotation of the abutment around the longitudinal axis of the implant is prevented when the abutment is arranged at the implant, such that the orientation of the abutment is fixed. For some applications, such as for multiple implant restoration units where some rotational freedom is advantageous, non-engaging abutments may be preferred. The correct arrangement of especially non-engaging abutments, such as non-engaging healing and implant abutments, in the implant depends on the expertise of the dentist.
In some cases an angled abutment must be used to support the anatomical layer. In such an abutment the longitudinal axis of the portion on which the anatomical layer is placed has an angle relative to the longitudinal axis of the portion which is inserted into the implant. This may be the case when the implant is titled relative to the sagittal plane of the patient,
In such cases it is important that a customized healing abutment is arranged correctly relative to the implant in order to provide that the soft tissue is shaped anatomically correct.
Likewise it may also be important that the implant abutment is arranged correctly relative to the implant in order to provide a good support for the anatomical layer, such as a crown layer or a crown portion of a bridge restoration.
Positioning jigs for confirming that the correct arrangement of a dental restoration in dental implant are known in the prior art. US2008153067 teaches a method for digitally designing an overmould which can be used to ensure a correct positioning of a customized abutment and implant analog in a physical model of a patient's set of teeth.
When a dentist needs access to the implant region while having the positioning jig arranged at the patient's set of teeth, e.g. for securing an implant abutment in the implant using a retention screw, a through hole is drilled in the manufactured positioning jig. This adds a further step to the manufacture of the positioning jig in which step there is a risk of damaging the manufactured jig
For the surgical drilling of a bore into the patient's jaw bone for the implant, a drill guide can be manufactured and arranged in the patient's mouth where it guides the dentist to drill the bore at a planned implant placement.
The implant placement can be planned based on a CT scan of the patient's set of teeth showing nerves and roots of neighboring teeth. From the planned position and orientation and the drill guide can be digitally designed and subsequently manufactured using direct digital manufacturing techniques.